Link following in wasm-micro-runtime - CVE-2025-43853
Published: April 24, 2026
Vulnerability identifier: #VU127496
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2025-43853
CWE-ID: CWE-59
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Bytecode Alliance
Affected software:
wasm-micro-runtime
wasm-micro-runtime
Detailed vulnerability description
The vulnerability allows a remote attacker to access files outside of the filesystem sandbox.
The vulnerability exists due to improper access control in the uvwasi filesystem handling when processing symlinks containing backslashes on Windows. A remote attacker can create a crafted symlink and open it to access files outside of the filesystem sandbox.
On Windows, the issue can also allow creation of a file on the host outside of the preopened directory when the symlink is opened with the create flag.
How to mitigate CVE-2025-43853
Install security update from vendor's website.